Bedtime Aspirin Lowers Ambulatory Blood Pressure

Sunday, October 11, 2009

By Will Boggs, MD

NEW YORK (Reuters Health) Aug 12 - Aspirin taken at bedtime reduces ambulatory blood pressure in patients with prehypertension, according to a report in the August issue of the American Journal of Hypertension.

"Bedtime ingestion of low-dose aspirin could provide a cost-effective approach for blood pressure control in subjects with prehypertension, thus delaying the actual development of hypertension and the need for costly pharmacologic treatment," Dr. Ramon C. Hermida from University of Vigo, Spain, told Reuters Health in an email.

Dr. Hermida and colleagues investigated the influence of aspirin on ambulatory blood pressure in patients who received aspirin at different times of the day according to their rest-activity cycle and who were evaluated by 48-hour ambulatory blood pressure monitoring before and after 3 months of pharmacologic intervention.

Blood pressure did not change after nonpharmacological intervention or after administration of aspirin upon awakening, the researchers note.

In contrast, the authors report, systolic blood pressure decreased by 6 mm Hg and diastolic blood pressure decreased by 3 mm Hg in patients who took 100 mg aspirin at bedtime.

Nearly three quarters (71%) of the patients who took aspirin at bedtime experienced at least a 3 mm Hg reduction in 24-hour systolic blood pressure, but only 6% showed an increase in blood pressure after treatment.

Heart rate was unchanged in all treatment groups.

"Aspirin given at the end of the activity cycle, but not upon awakening, could thus target the nocturnal peak of plasma renin activity, while enhancing the nocturnal trough in the production of nitric oxide," the investigators suggest.

"Thus," they continue, "the enhanced reduction in plasma renin activity, beneficial impact on endothelial function and blocking of alpha- and beta-adrenergic receptors associated (with) bedtime administration of low-dose aspirin could explain the impact of this intervention on blood pressure here documented in subjects with high-normal blood pressure."

"We are currently developing a new multicenter prospective trial with awakening versus bedtime administration of low-dose aspirin for primary prevention of cardiovascular events in subjects with impaired fasting glucose or diabetes," Dr. Hermida explained. "The study will involve 3200 subjects who will be followed for over 5 years."


Am J Hypertens 2009;22:896-903.


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